Is it *Safe* to drink hot water from a combi boiler?

[eveares]

Ah, I see: https://water.usgs.gov/edu/qa-chemical-cloudy.html

 

[big-all]

ok my thoughts
you have to draw off cold water from the pipes and disguard that water if you want warm or hot so waste water and heat as you now have pipework full off heated water now cooling
inn my opinion the effort is not worth the savings even without the possible risk
a cup off hot water will cost perhaps 0.05p or 20 cups to the penny
by prewarming you may get perhaps 30 cups per penny with wasted water
is the risk off water poisening worth the possible maybe 1 or 2p a day saving

 

[Corgigrouch GTi]

ok my thoughts
you have to draw off cold water from the pipes and disguard that water if you want warm or hot so waste water and heat as you now have pipework full off heated water now cooling
inn my opinion the effort is not worth the savings even without the possible risk
a cup off hot water will cost perhaps 0.05p or 20 cups to the penny
by prewarming you may get perhaps 30 cups per penny with wasted water
is the risk off water poisening worth the possible maybe 1 or 2p a day saving

How does heating the water make it toxic?

 

[FiremanT]

is the risk off water poisening worth the possible maybe 1 or 2p a day saving

Where id the Risk?

 

[bernardgreen]

How does heating the water make it toxic?

Warming water is supposed to increase the risk of legionella. Maybe the water in the DHW side of the plate exchanger gets warmed ( CH on but no DHW flow ) and while warm bacteria multiply. When DHW is called for the warm, bacteria loaded (?) water will be out of the plate heat exchanger and on it's way to the tap before the primary circuit is hot enough to kill bacteria.

EDIT not just the water in the plate echanger. water in the DHW pipe work inside the boiler casing will be warmed when the boiler is running.

And a pre-heat tank ?

 

[vulcancontinental]

It's designated Cat2, therefore not wholesome and not designated as drinking water. Would it kill you..... probably not ... although if the plate was leaking inhibited CH system water, it wouldn't be nice.

Right and yet not quite right.

When the water leaves the spout of the cold main tap it's cat 1, wholesome drinking water, when it's in the glass it's cat 2, if you add orange squash it's cat 3, if you leave it on a shelf for 6 months it's cat 5.

Interesting though because the only change in a combi is temperature, no exposure to anything else.

I was interested to learn that cat 3 and 4 are due to chemical contamination. Rust, metal particles from the system are not considered.

 

[oilboffin]

You are the man dan

 

[bernardgreen]

Might help to describe the catagories as defined by WRAS

https://www.wras.co.uk/consumers/resources/glossary/fluid_categories/

 

[Corgigrouch GTi]

Warming water is supposed to increase the risk of legionella. Maybe the water in the DHW side of the plate exchanger gets warmed ( CH on but no DHW flow ) and while warm bacteria multiply. When DHW is called for the warm, bacteria loaded (?) water will be out of the plate heat exchanger and on it's way to the tap before the primary circuit is hot enough to kill bacteria.

EDIT not just the water in the plate echanger. water in the DHW pipe work inside the boiler casing will be warmed when the boiler is running.

And a pre-heat tank ?

In which case, this applies to all water, since water that is stationary in a pipe in a heated room can promote the growth of Legionella...Good grief, it is amazing that any of us are still alive..

 

[bernardgreen]

In which case, this applies to all water, since water that is stationary in a pipe in a heated room can promote the growth of Legionella.

That would appear to be the case when cold water pipes are installed close to un-insulated heating pipes.

Good grief, it is amazing that any of us are still alive..

Don't worry, Health and Safety will save us all from the dangers that Health and Safety can dream up.

 

[Corgigrouch GTi]

Bernard, I do believe that you are beginning to develop a sense of humour.

 

[bernardgreen]

Bernard, I do believe that you are beginning to develop a sense of humour.

I am doomed.........

 

[big-all]

How does heating the water make it toxic?

i didnt say anything thing about toxic??
i dont think it poisonous but in case it may be
is just wasted water to draw off the cold and energy to heat the water now cooling in the pipework
just trying to put all the relevant information forward

 

[nickso]

Another consideration if you have changed to a combi is the manky old pipework that you didn't change when you converted it over from a tank fed system. Mine is 40 years old and the 1 inch layer of **** that was in the bottom of that tank went through those pipes too.

Probably won't kill you but I'd rather not drink it neat.

 

[shambolic]

Sh1t I must drain off all my hot and cold supplies and run it through this week as I'm off on holiday and the static water will get warm and kill me when I get home